Oh, I think it comes down to just one reason, really: that ya hate us cuz ya AIN'T us. Pathological envy + covetousness + sense of entitlement = narcissistic rage. How DARE gay people insist on being themselves, rather than just what you want them to be? Why, the NERVE!!! And of COURSE you really hate the "white" ones-- most of ya are too racist ("if even BLACK women can be women, why can't us MEN???") to wanna pod-people-ize/fuck anyone ELSE!

And, in one very important sense, I guess that you could say there's "no reason" for "transphobia"... as a WORD; as a concept. Since what the -phobia suffix denotes is an irrational fear of something. And, given their egomaniacal, unhinged, and abusive behavior... there's nothing irrational about fearing "trans" people.